4 * Copyright (C) 1991, 1992 Linus Torvalds
8 * Some corrections by tytso.
11 /* [Feb 1997 T. Schoebel-Theuer] Complete rewrite of the pathname
14 /* [Feb-Apr 2000, AV] Rewrite to the new namespace architecture.
17 #include <linux/init.h>
18 #include <linux/module.h>
19 #include <linux/slab.h>
21 #include <linux/namei.h>
22 #include <linux/quotaops.h>
23 #include <linux/pagemap.h>
24 #include <linux/fsnotify.h>
25 #include <linux/personality.h>
26 #include <linux/security.h>
27 #include <linux/syscalls.h>
28 #include <linux/mount.h>
29 #include <linux/audit.h>
30 #include <linux/capability.h>
31 #include <linux/file.h>
32 #include <linux/fcntl.h>
33 #include <linux/device_cgroup.h>
34 #include <asm/uaccess.h>
36 #define ACC_MODE(x) ("\000\004\002\006"[(x)&O_ACCMODE])
38 /* [Feb-1997 T. Schoebel-Theuer]
39 * Fundamental changes in the pathname lookup mechanisms (namei)
40 * were necessary because of omirr. The reason is that omirr needs
41 * to know the _real_ pathname, not the user-supplied one, in case
42 * of symlinks (and also when transname replacements occur).
44 * The new code replaces the old recursive symlink resolution with
45 * an iterative one (in case of non-nested symlink chains). It does
46 * this with calls to <fs>_follow_link().
47 * As a side effect, dir_namei(), _namei() and follow_link() are now
48 * replaced with a single function lookup_dentry() that can handle all
49 * the special cases of the former code.
51 * With the new dcache, the pathname is stored at each inode, at least as
52 * long as the refcount of the inode is positive. As a side effect, the
53 * size of the dcache depends on the inode cache and thus is dynamic.
55 * [29-Apr-1998 C. Scott Ananian] Updated above description of symlink
56 * resolution to correspond with current state of the code.
58 * Note that the symlink resolution is not *completely* iterative.
59 * There is still a significant amount of tail- and mid- recursion in
60 * the algorithm. Also, note that <fs>_readlink() is not used in
61 * lookup_dentry(): lookup_dentry() on the result of <fs>_readlink()
62 * may return different results than <fs>_follow_link(). Many virtual
63 * filesystems (including /proc) exhibit this behavior.
66 /* [24-Feb-97 T. Schoebel-Theuer] Side effects caused by new implementation:
67 * New symlink semantics: when open() is called with flags O_CREAT | O_EXCL
68 * and the name already exists in form of a symlink, try to create the new
69 * name indicated by the symlink. The old code always complained that the
70 * name already exists, due to not following the symlink even if its target
71 * is nonexistent. The new semantics affects also mknod() and link() when
72 * the name is a symlink pointing to a non-existant name.
74 * I don't know which semantics is the right one, since I have no access
75 * to standards. But I found by trial that HP-UX 9.0 has the full "new"
76 * semantics implemented, while SunOS 4.1.1 and Solaris (SunOS 5.4) have the
77 * "old" one. Personally, I think the new semantics is much more logical.
78 * Note that "ln old new" where "new" is a symlink pointing to a non-existing
79 * file does succeed in both HP-UX and SunOs, but not in Solaris
80 * and in the old Linux semantics.
83 /* [16-Dec-97 Kevin Buhr] For security reasons, we change some symlink
84 * semantics. See the comments in "open_namei" and "do_link" below.
86 * [10-Sep-98 Alan Modra] Another symlink change.
89 /* [Feb-Apr 2000 AV] Complete rewrite. Rules for symlinks:
90 * inside the path - always follow.
91 * in the last component in creation/removal/renaming - never follow.
92 * if LOOKUP_FOLLOW passed - follow.
93 * if the pathname has trailing slashes - follow.
94 * otherwise - don't follow.
95 * (applied in that order).
97 * [Jun 2000 AV] Inconsistent behaviour of open() in case if flags==O_CREAT
98 * restored for 2.4. This is the last surviving part of old 4.2BSD bug.
99 * During the 2.4 we need to fix the userland stuff depending on it -
100 * hopefully we will be able to get rid of that wart in 2.5. So far only
101 * XEmacs seems to be relying on it...
104 * [Sep 2001 AV] Single-semaphore locking scheme (kudos to David Holland)
105 * implemented. Let's see if raised priority of ->s_vfs_rename_mutex gives
106 * any extra contention...
109 static int __link_path_walk(const char *name
, struct nameidata
*nd
);
111 /* In order to reduce some races, while at the same time doing additional
112 * checking and hopefully speeding things up, we copy filenames to the
113 * kernel data space before using them..
115 * POSIX.1 2.4: an empty pathname is invalid (ENOENT).
116 * PATH_MAX includes the nul terminator --RR.
118 static int do_getname(const char __user
*filename
, char *page
)
121 unsigned long len
= PATH_MAX
;
123 if (!segment_eq(get_fs(), KERNEL_DS
)) {
124 if ((unsigned long) filename
>= TASK_SIZE
)
126 if (TASK_SIZE
- (unsigned long) filename
< PATH_MAX
)
127 len
= TASK_SIZE
- (unsigned long) filename
;
130 retval
= strncpy_from_user(page
, filename
, len
);
134 return -ENAMETOOLONG
;
140 char * getname(const char __user
* filename
)
144 result
= ERR_PTR(-ENOMEM
);
147 int retval
= do_getname(filename
, tmp
);
152 result
= ERR_PTR(retval
);
155 audit_getname(result
);
159 #ifdef CONFIG_AUDITSYSCALL
160 void putname(const char *name
)
162 if (unlikely(!audit_dummy_context()))
167 EXPORT_SYMBOL(putname
);
172 * generic_permission - check for access rights on a Posix-like filesystem
173 * @inode: inode to check access rights for
174 * @mask: right to check for (%MAY_READ, %MAY_WRITE, %MAY_EXEC)
175 * @check_acl: optional callback to check for Posix ACLs
177 * Used to check for read/write/execute permissions on a file.
178 * We use "fsuid" for this, letting us set arbitrary permissions
179 * for filesystem access without changing the "normal" uids which
180 * are used for other things..
182 int generic_permission(struct inode
*inode
, int mask
,
183 int (*check_acl
)(struct inode
*inode
, int mask
))
185 umode_t mode
= inode
->i_mode
;
187 mask
&= MAY_READ
| MAY_WRITE
| MAY_EXEC
;
189 if (current
->fsuid
== inode
->i_uid
)
192 if (IS_POSIXACL(inode
) && (mode
& S_IRWXG
) && check_acl
) {
193 int error
= check_acl(inode
, mask
);
194 if (error
== -EACCES
)
195 goto check_capabilities
;
196 else if (error
!= -EAGAIN
)
200 if (in_group_p(inode
->i_gid
))
205 * If the DACs are ok we don't need any capability check.
207 if ((mask
& ~mode
) == 0)
212 * Read/write DACs are always overridable.
213 * Executable DACs are overridable if at least one exec bit is set.
215 if (!(mask
& MAY_EXEC
) ||
216 (inode
->i_mode
& S_IXUGO
) || S_ISDIR(inode
->i_mode
))
217 if (capable(CAP_DAC_OVERRIDE
))
221 * Searching includes executable on directories, else just read.
223 if (mask
== MAY_READ
|| (S_ISDIR(inode
->i_mode
) && !(mask
& MAY_WRITE
)))
224 if (capable(CAP_DAC_READ_SEARCH
))
230 int permission(struct inode
*inode
, int mask
, struct nameidata
*nd
)
233 struct vfsmount
*mnt
= NULL
;
238 if (mask
& MAY_WRITE
) {
239 umode_t mode
= inode
->i_mode
;
242 * Nobody gets write access to a read-only fs.
244 if (IS_RDONLY(inode
) &&
245 (S_ISREG(mode
) || S_ISDIR(mode
) || S_ISLNK(mode
)))
249 * Nobody gets write access to an immutable file.
251 if (IS_IMMUTABLE(inode
))
255 if ((mask
& MAY_EXEC
) && S_ISREG(inode
->i_mode
)) {
257 * MAY_EXEC on regular files is denied if the fs is mounted
258 * with the "noexec" flag.
260 if (mnt
&& (mnt
->mnt_flags
& MNT_NOEXEC
))
264 /* Ordinary permission routines do not understand MAY_APPEND. */
265 if (inode
->i_op
&& inode
->i_op
->permission
) {
268 if (nd
->flags
& LOOKUP_OPEN
)
271 retval
= inode
->i_op
->permission(inode
, mask
| extra
);
274 * Exec permission on a regular file is denied if none
275 * of the execute bits are set.
277 * This check should be done by the ->permission()
280 if ((mask
& MAY_EXEC
) && S_ISREG(inode
->i_mode
) &&
281 !(inode
->i_mode
& S_IXUGO
))
285 retval
= generic_permission(inode
, mask
, NULL
);
290 retval
= devcgroup_inode_permission(inode
, mask
);
294 return security_inode_permission(inode
,
295 mask
& (MAY_READ
|MAY_WRITE
|MAY_EXEC
), nd
);
299 * vfs_permission - check for access rights to a given path
300 * @nd: lookup result that describes the path
301 * @mask: right to check for (%MAY_READ, %MAY_WRITE, %MAY_EXEC)
303 * Used to check for read/write/execute permissions on a path.
304 * We use "fsuid" for this, letting us set arbitrary permissions
305 * for filesystem access without changing the "normal" uids which
306 * are used for other things.
308 int vfs_permission(struct nameidata
*nd
, int mask
)
310 return permission(nd
->path
.dentry
->d_inode
, mask
, nd
);
314 * file_permission - check for additional access rights to a given file
315 * @file: file to check access rights for
316 * @mask: right to check for (%MAY_READ, %MAY_WRITE, %MAY_EXEC)
318 * Used to check for read/write/execute permissions on an already opened
322 * Do not use this function in new code. All access checks should
323 * be done using vfs_permission().
325 int file_permission(struct file
*file
, int mask
)
327 return permission(file
->f_path
.dentry
->d_inode
, mask
, NULL
);
331 * get_write_access() gets write permission for a file.
332 * put_write_access() releases this write permission.
333 * This is used for regular files.
334 * We cannot support write (and maybe mmap read-write shared) accesses and
335 * MAP_DENYWRITE mmappings simultaneously. The i_writecount field of an inode
336 * can have the following values:
337 * 0: no writers, no VM_DENYWRITE mappings
338 * < 0: (-i_writecount) vm_area_structs with VM_DENYWRITE set exist
339 * > 0: (i_writecount) users are writing to the file.
341 * Normally we operate on that counter with atomic_{inc,dec} and it's safe
342 * except for the cases where we don't hold i_writecount yet. Then we need to
343 * use {get,deny}_write_access() - these functions check the sign and refuse
344 * to do the change if sign is wrong. Exclusion between them is provided by
345 * the inode->i_lock spinlock.
348 int get_write_access(struct inode
* inode
)
350 spin_lock(&inode
->i_lock
);
351 if (atomic_read(&inode
->i_writecount
) < 0) {
352 spin_unlock(&inode
->i_lock
);
355 atomic_inc(&inode
->i_writecount
);
356 spin_unlock(&inode
->i_lock
);
361 int deny_write_access(struct file
* file
)
363 struct inode
*inode
= file
->f_path
.dentry
->d_inode
;
365 spin_lock(&inode
->i_lock
);
366 if (atomic_read(&inode
->i_writecount
) > 0) {
367 spin_unlock(&inode
->i_lock
);
370 atomic_dec(&inode
->i_writecount
);
371 spin_unlock(&inode
->i_lock
);
377 * path_get - get a reference to a path
378 * @path: path to get the reference to
380 * Given a path increment the reference count to the dentry and the vfsmount.
382 void path_get(struct path
*path
)
387 EXPORT_SYMBOL(path_get
);
390 * path_put - put a reference to a path
391 * @path: path to put the reference to
393 * Given a path decrement the reference count to the dentry and the vfsmount.
395 void path_put(struct path
*path
)
400 EXPORT_SYMBOL(path_put
);
403 * release_open_intent - free up open intent resources
404 * @nd: pointer to nameidata
406 void release_open_intent(struct nameidata
*nd
)
408 if (nd
->intent
.open
.file
->f_path
.dentry
== NULL
)
409 put_filp(nd
->intent
.open
.file
);
411 fput(nd
->intent
.open
.file
);
414 static inline struct dentry
*
415 do_revalidate(struct dentry
*dentry
, struct nameidata
*nd
)
417 int status
= dentry
->d_op
->d_revalidate(dentry
, nd
);
418 if (unlikely(status
<= 0)) {
420 * The dentry failed validation.
421 * If d_revalidate returned 0 attempt to invalidate
422 * the dentry otherwise d_revalidate is asking us
423 * to return a fail status.
426 if (!d_invalidate(dentry
)) {
432 dentry
= ERR_PTR(status
);
439 * Internal lookup() using the new generic dcache.
442 static struct dentry
* cached_lookup(struct dentry
* parent
, struct qstr
* name
, struct nameidata
*nd
)
444 struct dentry
* dentry
= __d_lookup(parent
, name
);
446 /* lockess __d_lookup may fail due to concurrent d_move()
447 * in some unrelated directory, so try with d_lookup
450 dentry
= d_lookup(parent
, name
);
452 if (dentry
&& dentry
->d_op
&& dentry
->d_op
->d_revalidate
)
453 dentry
= do_revalidate(dentry
, nd
);
459 * Short-cut version of permission(), for calling by
460 * path_walk(), when dcache lock is held. Combines parts
461 * of permission() and generic_permission(), and tests ONLY for
462 * MAY_EXEC permission.
464 * If appropriate, check DAC only. If not appropriate, or
465 * short-cut DAC fails, then call permission() to do more
466 * complete permission check.
468 static int exec_permission_lite(struct inode
*inode
,
469 struct nameidata
*nd
)
471 umode_t mode
= inode
->i_mode
;
473 if (inode
->i_op
&& inode
->i_op
->permission
)
476 if (current
->fsuid
== inode
->i_uid
)
478 else if (in_group_p(inode
->i_gid
))
484 if ((inode
->i_mode
& S_IXUGO
) && capable(CAP_DAC_OVERRIDE
))
487 if (S_ISDIR(inode
->i_mode
) && capable(CAP_DAC_OVERRIDE
))
490 if (S_ISDIR(inode
->i_mode
) && capable(CAP_DAC_READ_SEARCH
))
495 return security_inode_permission(inode
, MAY_EXEC
, nd
);
499 * This is called when everything else fails, and we actually have
500 * to go to the low-level filesystem to find out what we should do..
502 * We get the directory semaphore, and after getting that we also
503 * make sure that nobody added the entry to the dcache in the meantime..
506 static struct dentry
* real_lookup(struct dentry
* parent
, struct qstr
* name
, struct nameidata
*nd
)
508 struct dentry
* result
;
509 struct inode
*dir
= parent
->d_inode
;
511 mutex_lock(&dir
->i_mutex
);
513 * First re-do the cached lookup just in case it was created
514 * while we waited for the directory semaphore..
516 * FIXME! This could use version numbering or similar to
517 * avoid unnecessary cache lookups.
519 * The "dcache_lock" is purely to protect the RCU list walker
520 * from concurrent renames at this point (we mustn't get false
521 * negatives from the RCU list walk here, unlike the optimistic
524 * so doing d_lookup() (with seqlock), instead of lockfree __d_lookup
526 result
= d_lookup(parent
, name
);
528 struct dentry
*dentry
;
530 /* Don't create child dentry for a dead directory. */
531 result
= ERR_PTR(-ENOENT
);
535 dentry
= d_alloc(parent
, name
);
536 result
= ERR_PTR(-ENOMEM
);
538 result
= dir
->i_op
->lookup(dir
, dentry
, nd
);
545 mutex_unlock(&dir
->i_mutex
);
550 * Uhhuh! Nasty case: the cache was re-populated while
551 * we waited on the semaphore. Need to revalidate.
553 mutex_unlock(&dir
->i_mutex
);
554 if (result
->d_op
&& result
->d_op
->d_revalidate
) {
555 result
= do_revalidate(result
, nd
);
557 result
= ERR_PTR(-ENOENT
);
563 static __always_inline
void
564 walk_init_root(const char *name
, struct nameidata
*nd
)
566 struct fs_struct
*fs
= current
->fs
;
568 read_lock(&fs
->lock
);
571 read_unlock(&fs
->lock
);
575 * Wrapper to retry pathname resolution whenever the underlying
576 * file system returns an ESTALE.
578 * Retry the whole path once, forcing real lookup requests
579 * instead of relying on the dcache.
581 static __always_inline
int link_path_walk(const char *name
, struct nameidata
*nd
)
583 struct path save
= nd
->path
;
586 /* make sure the stuff we saved doesn't go away */
589 result
= __link_path_walk(name
, nd
);
590 if (result
== -ESTALE
) {
591 /* nd->path had been dropped */
594 nd
->flags
|= LOOKUP_REVAL
;
595 result
= __link_path_walk(name
, nd
);
603 static __always_inline
int __vfs_follow_link(struct nameidata
*nd
, const char *link
)
612 walk_init_root(link
, nd
);
614 res
= link_path_walk(link
, nd
);
615 if (nd
->depth
|| res
|| nd
->last_type
!=LAST_NORM
)
618 * If it is an iterative symlinks resolution in open_namei() we
619 * have to copy the last component. And all that crap because of
620 * bloody create() on broken symlinks. Furrfu...
623 if (unlikely(!name
)) {
627 strcpy(name
, nd
->last
.name
);
628 nd
->last
.name
= name
;
632 return PTR_ERR(link
);
635 static void path_put_conditional(struct path
*path
, struct nameidata
*nd
)
638 if (path
->mnt
!= nd
->path
.mnt
)
642 static inline void path_to_nameidata(struct path
*path
, struct nameidata
*nd
)
644 dput(nd
->path
.dentry
);
645 if (nd
->path
.mnt
!= path
->mnt
)
646 mntput(nd
->path
.mnt
);
647 nd
->path
.mnt
= path
->mnt
;
648 nd
->path
.dentry
= path
->dentry
;
651 static __always_inline
int __do_follow_link(struct path
*path
, struct nameidata
*nd
)
655 struct dentry
*dentry
= path
->dentry
;
657 touch_atime(path
->mnt
, dentry
);
658 nd_set_link(nd
, NULL
);
660 if (path
->mnt
!= nd
->path
.mnt
) {
661 path_to_nameidata(path
, nd
);
665 cookie
= dentry
->d_inode
->i_op
->follow_link(dentry
, nd
);
666 error
= PTR_ERR(cookie
);
667 if (!IS_ERR(cookie
)) {
668 char *s
= nd_get_link(nd
);
671 error
= __vfs_follow_link(nd
, s
);
672 if (dentry
->d_inode
->i_op
->put_link
)
673 dentry
->d_inode
->i_op
->put_link(dentry
, nd
, cookie
);
681 * This limits recursive symlink follows to 8, while
682 * limiting consecutive symlinks to 40.
684 * Without that kind of total limit, nasty chains of consecutive
685 * symlinks can cause almost arbitrarily long lookups.
687 static inline int do_follow_link(struct path
*path
, struct nameidata
*nd
)
690 if (current
->link_count
>= MAX_NESTED_LINKS
)
692 if (current
->total_link_count
>= 40)
694 BUG_ON(nd
->depth
>= MAX_NESTED_LINKS
);
696 err
= security_inode_follow_link(path
->dentry
, nd
);
699 current
->link_count
++;
700 current
->total_link_count
++;
702 err
= __do_follow_link(path
, nd
);
703 current
->link_count
--;
707 path_put_conditional(path
, nd
);
712 int follow_up(struct vfsmount
**mnt
, struct dentry
**dentry
)
714 struct vfsmount
*parent
;
715 struct dentry
*mountpoint
;
716 spin_lock(&vfsmount_lock
);
717 parent
=(*mnt
)->mnt_parent
;
718 if (parent
== *mnt
) {
719 spin_unlock(&vfsmount_lock
);
723 mountpoint
=dget((*mnt
)->mnt_mountpoint
);
724 spin_unlock(&vfsmount_lock
);
726 *dentry
= mountpoint
;
732 /* no need for dcache_lock, as serialization is taken care in
735 static int __follow_mount(struct path
*path
)
738 while (d_mountpoint(path
->dentry
)) {
739 struct vfsmount
*mounted
= lookup_mnt(path
->mnt
, path
->dentry
);
746 path
->dentry
= dget(mounted
->mnt_root
);
752 static void follow_mount(struct vfsmount
**mnt
, struct dentry
**dentry
)
754 while (d_mountpoint(*dentry
)) {
755 struct vfsmount
*mounted
= lookup_mnt(*mnt
, *dentry
);
761 *dentry
= dget(mounted
->mnt_root
);
765 /* no need for dcache_lock, as serialization is taken care in
768 int follow_down(struct vfsmount
**mnt
, struct dentry
**dentry
)
770 struct vfsmount
*mounted
;
772 mounted
= lookup_mnt(*mnt
, *dentry
);
777 *dentry
= dget(mounted
->mnt_root
);
783 static __always_inline
void follow_dotdot(struct nameidata
*nd
)
785 struct fs_struct
*fs
= current
->fs
;
788 struct vfsmount
*parent
;
789 struct dentry
*old
= nd
->path
.dentry
;
791 read_lock(&fs
->lock
);
792 if (nd
->path
.dentry
== fs
->root
.dentry
&&
793 nd
->path
.mnt
== fs
->root
.mnt
) {
794 read_unlock(&fs
->lock
);
797 read_unlock(&fs
->lock
);
798 spin_lock(&dcache_lock
);
799 if (nd
->path
.dentry
!= nd
->path
.mnt
->mnt_root
) {
800 nd
->path
.dentry
= dget(nd
->path
.dentry
->d_parent
);
801 spin_unlock(&dcache_lock
);
805 spin_unlock(&dcache_lock
);
806 spin_lock(&vfsmount_lock
);
807 parent
= nd
->path
.mnt
->mnt_parent
;
808 if (parent
== nd
->path
.mnt
) {
809 spin_unlock(&vfsmount_lock
);
813 nd
->path
.dentry
= dget(nd
->path
.mnt
->mnt_mountpoint
);
814 spin_unlock(&vfsmount_lock
);
816 mntput(nd
->path
.mnt
);
817 nd
->path
.mnt
= parent
;
819 follow_mount(&nd
->path
.mnt
, &nd
->path
.dentry
);
823 * It's more convoluted than I'd like it to be, but... it's still fairly
824 * small and for now I'd prefer to have fast path as straight as possible.
825 * It _is_ time-critical.
827 static int do_lookup(struct nameidata
*nd
, struct qstr
*name
,
830 struct vfsmount
*mnt
= nd
->path
.mnt
;
831 struct dentry
*dentry
= __d_lookup(nd
->path
.dentry
, name
);
835 if (dentry
->d_op
&& dentry
->d_op
->d_revalidate
)
836 goto need_revalidate
;
839 path
->dentry
= dentry
;
840 __follow_mount(path
);
844 dentry
= real_lookup(nd
->path
.dentry
, name
, nd
);
850 dentry
= do_revalidate(dentry
, nd
);
858 return PTR_ERR(dentry
);
863 * This is the basic name resolution function, turning a pathname into
864 * the final dentry. We expect 'base' to be positive and a directory.
866 * Returns 0 and nd will have valid dentry and mnt on success.
867 * Returns error and drops reference to input namei data on failure.
869 static int __link_path_walk(const char *name
, struct nameidata
*nd
)
874 unsigned int lookup_flags
= nd
->flags
;
881 inode
= nd
->path
.dentry
->d_inode
;
883 lookup_flags
= LOOKUP_FOLLOW
| (nd
->flags
& LOOKUP_CONTINUE
);
885 /* At this point we know we have a real path component. */
891 nd
->flags
|= LOOKUP_CONTINUE
;
892 err
= exec_permission_lite(inode
, nd
);
894 err
= vfs_permission(nd
, MAY_EXEC
);
899 c
= *(const unsigned char *)name
;
901 hash
= init_name_hash();
904 hash
= partial_name_hash(c
, hash
);
905 c
= *(const unsigned char *)name
;
906 } while (c
&& (c
!= '/'));
907 this.len
= name
- (const char *) this.name
;
908 this.hash
= end_name_hash(hash
);
910 /* remove trailing slashes? */
913 while (*++name
== '/');
915 goto last_with_slashes
;
918 * "." and ".." are special - ".." especially so because it has
919 * to be able to know about the current root directory and
920 * parent relationships.
922 if (this.name
[0] == '.') switch (this.len
) {
926 if (this.name
[1] != '.')
929 inode
= nd
->path
.dentry
->d_inode
;
935 * See if the low-level filesystem might want
936 * to use its own hash..
938 if (nd
->path
.dentry
->d_op
&& nd
->path
.dentry
->d_op
->d_hash
) {
939 err
= nd
->path
.dentry
->d_op
->d_hash(nd
->path
.dentry
,
944 /* This does the actual lookups.. */
945 err
= do_lookup(nd
, &this, &next
);
950 inode
= next
.dentry
->d_inode
;
957 if (inode
->i_op
->follow_link
) {
958 err
= do_follow_link(&next
, nd
);
962 inode
= nd
->path
.dentry
->d_inode
;
969 path_to_nameidata(&next
, nd
);
971 if (!inode
->i_op
->lookup
)
974 /* here ends the main loop */
977 lookup_flags
|= LOOKUP_FOLLOW
| LOOKUP_DIRECTORY
;
979 /* Clear LOOKUP_CONTINUE iff it was previously unset */
980 nd
->flags
&= lookup_flags
| ~LOOKUP_CONTINUE
;
981 if (lookup_flags
& LOOKUP_PARENT
)
983 if (this.name
[0] == '.') switch (this.len
) {
987 if (this.name
[1] != '.')
990 inode
= nd
->path
.dentry
->d_inode
;
995 if (nd
->path
.dentry
->d_op
&& nd
->path
.dentry
->d_op
->d_hash
) {
996 err
= nd
->path
.dentry
->d_op
->d_hash(nd
->path
.dentry
,
1001 err
= do_lookup(nd
, &this, &next
);
1004 inode
= next
.dentry
->d_inode
;
1005 if ((lookup_flags
& LOOKUP_FOLLOW
)
1006 && inode
&& inode
->i_op
&& inode
->i_op
->follow_link
) {
1007 err
= do_follow_link(&next
, nd
);
1010 inode
= nd
->path
.dentry
->d_inode
;
1012 path_to_nameidata(&next
, nd
);
1016 if (lookup_flags
& LOOKUP_DIRECTORY
) {
1018 if (!inode
->i_op
|| !inode
->i_op
->lookup
)
1024 nd
->last_type
= LAST_NORM
;
1025 if (this.name
[0] != '.')
1028 nd
->last_type
= LAST_DOT
;
1029 else if (this.len
== 2 && this.name
[1] == '.')
1030 nd
->last_type
= LAST_DOTDOT
;
1035 * We bypassed the ordinary revalidation routines.
1036 * We may need to check the cached dentry for staleness.
1038 if (nd
->path
.dentry
&& nd
->path
.dentry
->d_sb
&&
1039 (nd
->path
.dentry
->d_sb
->s_type
->fs_flags
& FS_REVAL_DOT
)) {
1041 /* Note: we do not d_invalidate() */
1042 if (!nd
->path
.dentry
->d_op
->d_revalidate(
1043 nd
->path
.dentry
, nd
))
1049 path_put_conditional(&next
, nd
);
1052 path_put(&nd
->path
);
1057 static int path_walk(const char *name
, struct nameidata
*nd
)
1059 current
->total_link_count
= 0;
1060 return link_path_walk(name
, nd
);
1063 /* Returns 0 and nd will be valid on success; Retuns error, otherwise. */
1064 static int do_path_lookup(int dfd
, const char *name
,
1065 unsigned int flags
, struct nameidata
*nd
)
1070 struct fs_struct
*fs
= current
->fs
;
1072 nd
->last_type
= LAST_ROOT
; /* if there are only slashes... */
1077 read_lock(&fs
->lock
);
1078 nd
->path
= fs
->root
;
1079 path_get(&fs
->root
);
1080 read_unlock(&fs
->lock
);
1081 } else if (dfd
== AT_FDCWD
) {
1082 read_lock(&fs
->lock
);
1085 read_unlock(&fs
->lock
);
1087 struct dentry
*dentry
;
1089 file
= fget_light(dfd
, &fput_needed
);
1094 dentry
= file
->f_path
.dentry
;
1097 if (!S_ISDIR(dentry
->d_inode
->i_mode
))
1100 retval
= file_permission(file
, MAY_EXEC
);
1104 nd
->path
= file
->f_path
;
1105 path_get(&file
->f_path
);
1107 fput_light(file
, fput_needed
);
1110 retval
= path_walk(name
, nd
);
1111 if (unlikely(!retval
&& !audit_dummy_context() && nd
->path
.dentry
&&
1112 nd
->path
.dentry
->d_inode
))
1113 audit_inode(name
, nd
->path
.dentry
);
1118 fput_light(file
, fput_needed
);
1122 int path_lookup(const char *name
, unsigned int flags
,
1123 struct nameidata
*nd
)
1125 return do_path_lookup(AT_FDCWD
, name
, flags
, nd
);
1129 * vfs_path_lookup - lookup a file path relative to a dentry-vfsmount pair
1130 * @dentry: pointer to dentry of the base directory
1131 * @mnt: pointer to vfs mount of the base directory
1132 * @name: pointer to file name
1133 * @flags: lookup flags
1134 * @nd: pointer to nameidata
1136 int vfs_path_lookup(struct dentry
*dentry
, struct vfsmount
*mnt
,
1137 const char *name
, unsigned int flags
,
1138 struct nameidata
*nd
)
1142 /* same as do_path_lookup */
1143 nd
->last_type
= LAST_ROOT
;
1147 nd
->path
.dentry
= dentry
;
1149 path_get(&nd
->path
);
1151 retval
= path_walk(name
, nd
);
1152 if (unlikely(!retval
&& !audit_dummy_context() && nd
->path
.dentry
&&
1153 nd
->path
.dentry
->d_inode
))
1154 audit_inode(name
, nd
->path
.dentry
);
1160 static int __path_lookup_intent_open(int dfd
, const char *name
,
1161 unsigned int lookup_flags
, struct nameidata
*nd
,
1162 int open_flags
, int create_mode
)
1164 struct file
*filp
= get_empty_filp();
1169 nd
->intent
.open
.file
= filp
;
1170 nd
->intent
.open
.flags
= open_flags
;
1171 nd
->intent
.open
.create_mode
= create_mode
;
1172 err
= do_path_lookup(dfd
, name
, lookup_flags
|LOOKUP_OPEN
, nd
);
1173 if (IS_ERR(nd
->intent
.open
.file
)) {
1175 err
= PTR_ERR(nd
->intent
.open
.file
);
1176 path_put(&nd
->path
);
1178 } else if (err
!= 0)
1179 release_open_intent(nd
);
1184 * path_lookup_open - lookup a file path with open intent
1185 * @dfd: the directory to use as base, or AT_FDCWD
1186 * @name: pointer to file name
1187 * @lookup_flags: lookup intent flags
1188 * @nd: pointer to nameidata
1189 * @open_flags: open intent flags
1191 int path_lookup_open(int dfd
, const char *name
, unsigned int lookup_flags
,
1192 struct nameidata
*nd
, int open_flags
)
1194 return __path_lookup_intent_open(dfd
, name
, lookup_flags
, nd
,
1199 * path_lookup_create - lookup a file path with open + create intent
1200 * @dfd: the directory to use as base, or AT_FDCWD
1201 * @name: pointer to file name
1202 * @lookup_flags: lookup intent flags
1203 * @nd: pointer to nameidata
1204 * @open_flags: open intent flags
1205 * @create_mode: create intent flags
1207 static int path_lookup_create(int dfd
, const char *name
,
1208 unsigned int lookup_flags
, struct nameidata
*nd
,
1209 int open_flags
, int create_mode
)
1211 return __path_lookup_intent_open(dfd
, name
, lookup_flags
|LOOKUP_CREATE
,
1212 nd
, open_flags
, create_mode
);
1215 int __user_path_lookup_open(const char __user
*name
, unsigned int lookup_flags
,
1216 struct nameidata
*nd
, int open_flags
)
1218 char *tmp
= getname(name
);
1219 int err
= PTR_ERR(tmp
);
1222 err
= __path_lookup_intent_open(AT_FDCWD
, tmp
, lookup_flags
, nd
, open_flags
, 0);
1228 static struct dentry
*__lookup_hash(struct qstr
*name
,
1229 struct dentry
*base
, struct nameidata
*nd
)
1231 struct dentry
*dentry
;
1232 struct inode
*inode
;
1235 inode
= base
->d_inode
;
1238 * See if the low-level filesystem might want
1239 * to use its own hash..
1241 if (base
->d_op
&& base
->d_op
->d_hash
) {
1242 err
= base
->d_op
->d_hash(base
, name
);
1243 dentry
= ERR_PTR(err
);
1248 dentry
= cached_lookup(base
, name
, nd
);
1252 /* Don't create child dentry for a dead directory. */
1253 dentry
= ERR_PTR(-ENOENT
);
1254 if (IS_DEADDIR(inode
))
1257 new = d_alloc(base
, name
);
1258 dentry
= ERR_PTR(-ENOMEM
);
1261 dentry
= inode
->i_op
->lookup(inode
, new, nd
);
1272 * Restricted form of lookup. Doesn't follow links, single-component only,
1273 * needs parent already locked. Doesn't follow mounts.
1276 static struct dentry
*lookup_hash(struct nameidata
*nd
)
1280 err
= permission(nd
->path
.dentry
->d_inode
, MAY_EXEC
, nd
);
1282 return ERR_PTR(err
);
1283 return __lookup_hash(&nd
->last
, nd
->path
.dentry
, nd
);
1286 static int __lookup_one_len(const char *name
, struct qstr
*this,
1287 struct dentry
*base
, int len
)
1297 hash
= init_name_hash();
1299 c
= *(const unsigned char *)name
++;
1300 if (c
== '/' || c
== '\0')
1302 hash
= partial_name_hash(c
, hash
);
1304 this->hash
= end_name_hash(hash
);
1309 * lookup_one_len - filesystem helper to lookup single pathname component
1310 * @name: pathname component to lookup
1311 * @base: base directory to lookup from
1312 * @len: maximum length @len should be interpreted to
1314 * Note that this routine is purely a helper for filesystem usage and should
1315 * not be called by generic code. Also note that by using this function the
1316 * nameidata argument is passed to the filesystem methods and a filesystem
1317 * using this helper needs to be prepared for that.
1319 struct dentry
*lookup_one_len(const char *name
, struct dentry
*base
, int len
)
1324 err
= __lookup_one_len(name
, &this, base
, len
);
1326 return ERR_PTR(err
);
1328 err
= permission(base
->d_inode
, MAY_EXEC
, NULL
);
1330 return ERR_PTR(err
);
1331 return __lookup_hash(&this, base
, NULL
);
1335 * lookup_one_noperm - bad hack for sysfs
1336 * @name: pathname component to lookup
1337 * @base: base directory to lookup from
1339 * This is a variant of lookup_one_len that doesn't perform any permission
1340 * checks. It's a horrible hack to work around the braindead sysfs
1341 * architecture and should not be used anywhere else.
1343 * DON'T USE THIS FUNCTION EVER, thanks.
1345 struct dentry
*lookup_one_noperm(const char *name
, struct dentry
*base
)
1350 err
= __lookup_one_len(name
, &this, base
, strlen(name
));
1352 return ERR_PTR(err
);
1353 return __lookup_hash(&this, base
, NULL
);
1356 int __user_walk_fd(int dfd
, const char __user
*name
, unsigned flags
,
1357 struct nameidata
*nd
)
1359 char *tmp
= getname(name
);
1360 int err
= PTR_ERR(tmp
);
1363 err
= do_path_lookup(dfd
, tmp
, flags
, nd
);
1369 int __user_walk(const char __user
*name
, unsigned flags
, struct nameidata
*nd
)
1371 return __user_walk_fd(AT_FDCWD
, name
, flags
, nd
);
1375 * It's inline, so penalty for filesystems that don't use sticky bit is
1378 static inline int check_sticky(struct inode
*dir
, struct inode
*inode
)
1380 if (!(dir
->i_mode
& S_ISVTX
))
1382 if (inode
->i_uid
== current
->fsuid
)
1384 if (dir
->i_uid
== current
->fsuid
)
1386 return !capable(CAP_FOWNER
);
1390 * Check whether we can remove a link victim from directory dir, check
1391 * whether the type of victim is right.
1392 * 1. We can't do it if dir is read-only (done in permission())
1393 * 2. We should have write and exec permissions on dir
1394 * 3. We can't remove anything from append-only dir
1395 * 4. We can't do anything with immutable dir (done in permission())
1396 * 5. If the sticky bit on dir is set we should either
1397 * a. be owner of dir, or
1398 * b. be owner of victim, or
1399 * c. have CAP_FOWNER capability
1400 * 6. If the victim is append-only or immutable we can't do antyhing with
1401 * links pointing to it.
1402 * 7. If we were asked to remove a directory and victim isn't one - ENOTDIR.
1403 * 8. If we were asked to remove a non-directory and victim isn't one - EISDIR.
1404 * 9. We can't remove a root or mountpoint.
1405 * 10. We don't allow removal of NFS sillyrenamed files; it's handled by
1406 * nfs_async_unlink().
1408 static int may_delete(struct inode
*dir
,struct dentry
*victim
,int isdir
)
1412 if (!victim
->d_inode
)
1415 BUG_ON(victim
->d_parent
->d_inode
!= dir
);
1416 audit_inode_child(victim
->d_name
.name
, victim
, dir
);
1418 error
= permission(dir
,MAY_WRITE
| MAY_EXEC
, NULL
);
1423 if (check_sticky(dir
, victim
->d_inode
)||IS_APPEND(victim
->d_inode
)||
1424 IS_IMMUTABLE(victim
->d_inode
))
1427 if (!S_ISDIR(victim
->d_inode
->i_mode
))
1429 if (IS_ROOT(victim
))
1431 } else if (S_ISDIR(victim
->d_inode
->i_mode
))
1433 if (IS_DEADDIR(dir
))
1435 if (victim
->d_flags
& DCACHE_NFSFS_RENAMED
)
1440 /* Check whether we can create an object with dentry child in directory
1442 * 1. We can't do it if child already exists (open has special treatment for
1443 * this case, but since we are inlined it's OK)
1444 * 2. We can't do it if dir is read-only (done in permission())
1445 * 3. We should have write and exec permissions on dir
1446 * 4. We can't do it if dir is immutable (done in permission())
1448 static inline int may_create(struct inode
*dir
, struct dentry
*child
,
1449 struct nameidata
*nd
)
1453 if (IS_DEADDIR(dir
))
1455 return permission(dir
,MAY_WRITE
| MAY_EXEC
, nd
);
1459 * O_DIRECTORY translates into forcing a directory lookup.
1461 static inline int lookup_flags(unsigned int f
)
1463 unsigned long retval
= LOOKUP_FOLLOW
;
1466 retval
&= ~LOOKUP_FOLLOW
;
1468 if (f
& O_DIRECTORY
)
1469 retval
|= LOOKUP_DIRECTORY
;
1475 * p1 and p2 should be directories on the same fs.
1477 struct dentry
*lock_rename(struct dentry
*p1
, struct dentry
*p2
)
1482 mutex_lock_nested(&p1
->d_inode
->i_mutex
, I_MUTEX_PARENT
);
1486 mutex_lock(&p1
->d_inode
->i_sb
->s_vfs_rename_mutex
);
1488 for (p
= p1
; p
->d_parent
!= p
; p
= p
->d_parent
) {
1489 if (p
->d_parent
== p2
) {
1490 mutex_lock_nested(&p2
->d_inode
->i_mutex
, I_MUTEX_PARENT
);
1491 mutex_lock_nested(&p1
->d_inode
->i_mutex
, I_MUTEX_CHILD
);
1496 for (p
= p2
; p
->d_parent
!= p
; p
= p
->d_parent
) {
1497 if (p
->d_parent
== p1
) {
1498 mutex_lock_nested(&p1
->d_inode
->i_mutex
, I_MUTEX_PARENT
);
1499 mutex_lock_nested(&p2
->d_inode
->i_mutex
, I_MUTEX_CHILD
);
1504 mutex_lock_nested(&p1
->d_inode
->i_mutex
, I_MUTEX_PARENT
);
1505 mutex_lock_nested(&p2
->d_inode
->i_mutex
, I_MUTEX_CHILD
);
1509 void unlock_rename(struct dentry
*p1
, struct dentry
*p2
)
1511 mutex_unlock(&p1
->d_inode
->i_mutex
);
1513 mutex_unlock(&p2
->d_inode
->i_mutex
);
1514 mutex_unlock(&p1
->d_inode
->i_sb
->s_vfs_rename_mutex
);
1518 int vfs_create(struct inode
*dir
, struct dentry
*dentry
, int mode
,
1519 struct nameidata
*nd
)
1521 int error
= may_create(dir
, dentry
, nd
);
1526 if (!dir
->i_op
|| !dir
->i_op
->create
)
1527 return -EACCES
; /* shouldn't it be ENOSYS? */
1530 error
= security_inode_create(dir
, dentry
, mode
);
1534 error
= dir
->i_op
->create(dir
, dentry
, mode
, nd
);
1536 fsnotify_create(dir
, dentry
);
1540 int may_open(struct nameidata
*nd
, int acc_mode
, int flag
)
1542 struct dentry
*dentry
= nd
->path
.dentry
;
1543 struct inode
*inode
= dentry
->d_inode
;
1549 if (S_ISLNK(inode
->i_mode
))
1552 if (S_ISDIR(inode
->i_mode
) && (acc_mode
& MAY_WRITE
))
1556 * FIFO's, sockets and device files are special: they don't
1557 * actually live on the filesystem itself, and as such you
1558 * can write to them even if the filesystem is read-only.
1560 if (S_ISFIFO(inode
->i_mode
) || S_ISSOCK(inode
->i_mode
)) {
1562 } else if (S_ISBLK(inode
->i_mode
) || S_ISCHR(inode
->i_mode
)) {
1563 if (nd
->path
.mnt
->mnt_flags
& MNT_NODEV
)
1569 error
= vfs_permission(nd
, acc_mode
);
1573 * An append-only file must be opened in append mode for writing.
1575 if (IS_APPEND(inode
)) {
1576 if ((flag
& FMODE_WRITE
) && !(flag
& O_APPEND
))
1582 /* O_NOATIME can only be set by the owner or superuser */
1583 if (flag
& O_NOATIME
)
1584 if (!is_owner_or_cap(inode
))
1588 * Ensure there are no outstanding leases on the file.
1590 error
= break_lease(inode
, flag
);
1594 if (flag
& O_TRUNC
) {
1595 error
= get_write_access(inode
);
1600 * Refuse to truncate files with mandatory locks held on them.
1602 error
= locks_verify_locked(inode
);
1606 error
= do_truncate(dentry
, 0,
1607 ATTR_MTIME
|ATTR_CTIME
|ATTR_OPEN
,
1610 put_write_access(inode
);
1614 if (flag
& FMODE_WRITE
)
1621 * Be careful about ever adding any more callers of this
1622 * function. Its flags must be in the namei format, not
1623 * what get passed to sys_open().
1625 static int __open_namei_create(struct nameidata
*nd
, struct path
*path
,
1629 struct dentry
*dir
= nd
->path
.dentry
;
1631 if (!IS_POSIXACL(dir
->d_inode
))
1632 mode
&= ~current
->fs
->umask
;
1633 error
= vfs_create(dir
->d_inode
, path
->dentry
, mode
, nd
);
1634 mutex_unlock(&dir
->d_inode
->i_mutex
);
1635 dput(nd
->path
.dentry
);
1636 nd
->path
.dentry
= path
->dentry
;
1639 /* Don't check for write permission, don't truncate */
1640 return may_open(nd
, 0, flag
& ~O_TRUNC
);
1644 * Note that while the flag value (low two bits) for sys_open means:
1649 * it is changed into
1650 * 00 - no permissions needed
1651 * 01 - read-permission
1652 * 10 - write-permission
1654 * for the internal routines (ie open_namei()/follow_link() etc)
1655 * This is more logical, and also allows the 00 "no perm needed"
1656 * to be used for symlinks (where the permissions are checked
1660 static inline int open_to_namei_flags(int flag
)
1662 if ((flag
+1) & O_ACCMODE
)
1667 static int open_will_write_to_fs(int flag
, struct inode
*inode
)
1670 * We'll never write to the fs underlying
1673 if (special_file(inode
->i_mode
))
1675 return (flag
& O_TRUNC
);
1679 * Note that the low bits of the passed in "open_flag"
1680 * are not the same as in the local variable "flag". See
1681 * open_to_namei_flags() for more details.
1683 struct file
*do_filp_open(int dfd
, const char *pathname
,
1684 int open_flag
, int mode
)
1687 struct nameidata nd
;
1688 int acc_mode
, error
;
1693 int flag
= open_to_namei_flags(open_flag
);
1695 acc_mode
= ACC_MODE(flag
);
1697 /* O_TRUNC implies we need access checks for write permissions */
1699 acc_mode
|= MAY_WRITE
;
1701 /* Allow the LSM permission hook to distinguish append
1702 access from general write access. */
1703 if (flag
& O_APPEND
)
1704 acc_mode
|= MAY_APPEND
;
1707 * The simplest case - just a plain lookup.
1709 if (!(flag
& O_CREAT
)) {
1710 error
= path_lookup_open(dfd
, pathname
, lookup_flags(flag
),
1713 return ERR_PTR(error
);
1718 * Create - we need to know the parent.
1720 error
= path_lookup_create(dfd
, pathname
, LOOKUP_PARENT
,
1723 return ERR_PTR(error
);
1726 * We have the parent and last component. First of all, check
1727 * that we are not asked to creat(2) an obvious directory - that
1731 if (nd
.last_type
!= LAST_NORM
|| nd
.last
.name
[nd
.last
.len
])
1734 dir
= nd
.path
.dentry
;
1735 nd
.flags
&= ~LOOKUP_PARENT
;
1736 mutex_lock(&dir
->d_inode
->i_mutex
);
1737 path
.dentry
= lookup_hash(&nd
);
1738 path
.mnt
= nd
.path
.mnt
;
1741 error
= PTR_ERR(path
.dentry
);
1742 if (IS_ERR(path
.dentry
)) {
1743 mutex_unlock(&dir
->d_inode
->i_mutex
);
1747 if (IS_ERR(nd
.intent
.open
.file
)) {
1748 error
= PTR_ERR(nd
.intent
.open
.file
);
1749 goto exit_mutex_unlock
;
1752 /* Negative dentry, just create the file */
1753 if (!path
.dentry
->d_inode
) {
1755 * This write is needed to ensure that a
1756 * ro->rw transition does not occur between
1757 * the time when the file is created and when
1758 * a permanent write count is taken through
1759 * the 'struct file' in nameidata_to_filp().
1761 error
= mnt_want_write(nd
.path
.mnt
);
1763 goto exit_mutex_unlock
;
1764 error
= __open_namei_create(&nd
, &path
, flag
, mode
);
1766 mnt_drop_write(nd
.path
.mnt
);
1769 filp
= nameidata_to_filp(&nd
, open_flag
);
1770 mnt_drop_write(nd
.path
.mnt
);
1775 * It already exists.
1777 mutex_unlock(&dir
->d_inode
->i_mutex
);
1778 audit_inode(pathname
, path
.dentry
);
1784 if (__follow_mount(&path
)) {
1786 if (flag
& O_NOFOLLOW
)
1791 if (!path
.dentry
->d_inode
)
1793 if (path
.dentry
->d_inode
->i_op
&& path
.dentry
->d_inode
->i_op
->follow_link
)
1796 path_to_nameidata(&path
, &nd
);
1798 if (path
.dentry
->d_inode
&& S_ISDIR(path
.dentry
->d_inode
->i_mode
))
1803 * 1. may_open() truncates a file
1804 * 2. a rw->ro mount transition occurs
1805 * 3. nameidata_to_filp() fails due to
1807 * That would be inconsistent, and should
1808 * be avoided. Taking this mnt write here
1809 * ensures that (2) can not occur.
1811 will_write
= open_will_write_to_fs(flag
, nd
.path
.dentry
->d_inode
);
1813 error
= mnt_want_write(nd
.path
.mnt
);
1817 error
= may_open(&nd
, acc_mode
, flag
);
1820 mnt_drop_write(nd
.path
.mnt
);
1823 filp
= nameidata_to_filp(&nd
, open_flag
);
1825 * It is now safe to drop the mnt write
1826 * because the filp has had a write taken
1830 mnt_drop_write(nd
.path
.mnt
);
1834 mutex_unlock(&dir
->d_inode
->i_mutex
);
1836 path_put_conditional(&path
, &nd
);
1838 if (!IS_ERR(nd
.intent
.open
.file
))
1839 release_open_intent(&nd
);
1841 return ERR_PTR(error
);
1845 if (flag
& O_NOFOLLOW
)
1848 * This is subtle. Instead of calling do_follow_link() we do the
1849 * thing by hands. The reason is that this way we have zero link_count
1850 * and path_walk() (called from ->follow_link) honoring LOOKUP_PARENT.
1851 * After that we have the parent and last component, i.e.
1852 * we are in the same situation as after the first path_walk().
1853 * Well, almost - if the last component is normal we get its copy
1854 * stored in nd->last.name and we will have to putname() it when we
1855 * are done. Procfs-like symlinks just set LAST_BIND.
1857 nd
.flags
|= LOOKUP_PARENT
;
1858 error
= security_inode_follow_link(path
.dentry
, &nd
);
1861 error
= __do_follow_link(&path
, &nd
);
1863 /* Does someone understand code flow here? Or it is only
1864 * me so stupid? Anathema to whoever designed this non-sense
1865 * with "intent.open".
1867 release_open_intent(&nd
);
1868 return ERR_PTR(error
);
1870 nd
.flags
&= ~LOOKUP_PARENT
;
1871 if (nd
.last_type
== LAST_BIND
)
1874 if (nd
.last_type
!= LAST_NORM
)
1876 if (nd
.last
.name
[nd
.last
.len
]) {
1877 __putname(nd
.last
.name
);
1882 __putname(nd
.last
.name
);
1885 dir
= nd
.path
.dentry
;
1886 mutex_lock(&dir
->d_inode
->i_mutex
);
1887 path
.dentry
= lookup_hash(&nd
);
1888 path
.mnt
= nd
.path
.mnt
;
1889 __putname(nd
.last
.name
);
1894 * filp_open - open file and return file pointer
1896 * @filename: path to open
1897 * @flags: open flags as per the open(2) second argument
1898 * @mode: mode for the new file if O_CREAT is set, else ignored
1900 * This is the helper to open a file from kernelspace if you really
1901 * have to. But in generally you should not do this, so please move
1902 * along, nothing to see here..
1904 struct file
*filp_open(const char *filename
, int flags
, int mode
)
1906 return do_filp_open(AT_FDCWD
, filename
, flags
, mode
);
1908 EXPORT_SYMBOL(filp_open
);
1911 * lookup_create - lookup a dentry, creating it if it doesn't exist
1912 * @nd: nameidata info
1913 * @is_dir: directory flag
1915 * Simple function to lookup and return a dentry and create it
1916 * if it doesn't exist. Is SMP-safe.
1918 * Returns with nd->path.dentry->d_inode->i_mutex locked.
1920 struct dentry
*lookup_create(struct nameidata
*nd
, int is_dir
)
1922 struct dentry
*dentry
= ERR_PTR(-EEXIST
);
1924 mutex_lock_nested(&nd
->path
.dentry
->d_inode
->i_mutex
, I_MUTEX_PARENT
);
1926 * Yucky last component or no last component at all?
1927 * (foo/., foo/.., /////)
1929 if (nd
->last_type
!= LAST_NORM
)
1931 nd
->flags
&= ~LOOKUP_PARENT
;
1932 nd
->flags
|= LOOKUP_CREATE
;
1933 nd
->intent
.open
.flags
= O_EXCL
;
1936 * Do the final lookup.
1938 dentry
= lookup_hash(nd
);
1942 if (dentry
->d_inode
)
1945 * Special case - lookup gave negative, but... we had foo/bar/
1946 * From the vfs_mknod() POV we just have a negative dentry -
1947 * all is fine. Let's be bastards - you had / on the end, you've
1948 * been asking for (non-existent) directory. -ENOENT for you.
1950 if (unlikely(!is_dir
&& nd
->last
.name
[nd
->last
.len
])) {
1952 dentry
= ERR_PTR(-ENOENT
);
1957 dentry
= ERR_PTR(-EEXIST
);
1961 EXPORT_SYMBOL_GPL(lookup_create
);
1963 int vfs_mknod(struct inode
*dir
, struct dentry
*dentry
, int mode
, dev_t dev
)
1965 int error
= may_create(dir
, dentry
, NULL
);
1970 if ((S_ISCHR(mode
) || S_ISBLK(mode
)) && !capable(CAP_MKNOD
))
1973 if (!dir
->i_op
|| !dir
->i_op
->mknod
)
1976 error
= devcgroup_inode_mknod(mode
, dev
);
1980 error
= security_inode_mknod(dir
, dentry
, mode
, dev
);
1985 error
= dir
->i_op
->mknod(dir
, dentry
, mode
, dev
);
1987 fsnotify_create(dir
, dentry
);
1991 static int may_mknod(mode_t mode
)
1993 switch (mode
& S_IFMT
) {
1999 case 0: /* zero mode translates to S_IFREG */
2008 asmlinkage
long sys_mknodat(int dfd
, const char __user
*filename
, int mode
,
2013 struct dentry
* dentry
;
2014 struct nameidata nd
;
2018 tmp
= getname(filename
);
2020 return PTR_ERR(tmp
);
2022 error
= do_path_lookup(dfd
, tmp
, LOOKUP_PARENT
, &nd
);
2025 dentry
= lookup_create(&nd
, 0);
2026 if (IS_ERR(dentry
)) {
2027 error
= PTR_ERR(dentry
);
2030 if (!IS_POSIXACL(nd
.path
.dentry
->d_inode
))
2031 mode
&= ~current
->fs
->umask
;
2032 error
= may_mknod(mode
);
2035 error
= mnt_want_write(nd
.path
.mnt
);
2038 switch (mode
& S_IFMT
) {
2039 case 0: case S_IFREG
:
2040 error
= vfs_create(nd
.path
.dentry
->d_inode
,dentry
,mode
,&nd
);
2042 case S_IFCHR
: case S_IFBLK
:
2043 error
= vfs_mknod(nd
.path
.dentry
->d_inode
,dentry
,mode
,
2044 new_decode_dev(dev
));
2046 case S_IFIFO
: case S_IFSOCK
:
2047 error
= vfs_mknod(nd
.path
.dentry
->d_inode
,dentry
,mode
,0);
2050 mnt_drop_write(nd
.path
.mnt
);
2054 mutex_unlock(&nd
.path
.dentry
->d_inode
->i_mutex
);
2062 asmlinkage
long sys_mknod(const char __user
*filename
, int mode
, unsigned dev
)
2064 return sys_mknodat(AT_FDCWD
, filename
, mode
, dev
);
2067 int vfs_mkdir(struct inode
*dir
, struct dentry
*dentry
, int mode
)
2069 int error
= may_create(dir
, dentry
, NULL
);
2074 if (!dir
->i_op
|| !dir
->i_op
->mkdir
)
2077 mode
&= (S_IRWXUGO
|S_ISVTX
);
2078 error
= security_inode_mkdir(dir
, dentry
, mode
);
2083 error
= dir
->i_op
->mkdir(dir
, dentry
, mode
);
2085 fsnotify_mkdir(dir
, dentry
);
2089 asmlinkage
long sys_mkdirat(int dfd
, const char __user
*pathname
, int mode
)
2093 struct dentry
*dentry
;
2094 struct nameidata nd
;
2096 tmp
= getname(pathname
);
2097 error
= PTR_ERR(tmp
);
2101 error
= do_path_lookup(dfd
, tmp
, LOOKUP_PARENT
, &nd
);
2104 dentry
= lookup_create(&nd
, 1);
2105 error
= PTR_ERR(dentry
);
2109 if (!IS_POSIXACL(nd
.path
.dentry
->d_inode
))
2110 mode
&= ~current
->fs
->umask
;
2111 error
= mnt_want_write(nd
.path
.mnt
);
2114 error
= vfs_mkdir(nd
.path
.dentry
->d_inode
, dentry
, mode
);
2115 mnt_drop_write(nd
.path
.mnt
);
2119 mutex_unlock(&nd
.path
.dentry
->d_inode
->i_mutex
);
2127 asmlinkage
long sys_mkdir(const char __user
*pathname
, int mode
)
2129 return sys_mkdirat(AT_FDCWD
, pathname
, mode
);
2133 * We try to drop the dentry early: we should have
2134 * a usage count of 2 if we're the only user of this
2135 * dentry, and if that is true (possibly after pruning
2136 * the dcache), then we drop the dentry now.
2138 * A low-level filesystem can, if it choses, legally
2141 * if (!d_unhashed(dentry))
2144 * if it cannot handle the case of removing a directory
2145 * that is still in use by something else..
2147 void dentry_unhash(struct dentry
*dentry
)
2150 shrink_dcache_parent(dentry
);
2151 spin_lock(&dcache_lock
);
2152 spin_lock(&dentry
->d_lock
);
2153 if (atomic_read(&dentry
->d_count
) == 2)
2155 spin_unlock(&dentry
->d_lock
);
2156 spin_unlock(&dcache_lock
);
2159 int vfs_rmdir(struct inode
*dir
, struct dentry
*dentry
)
2161 int error
= may_delete(dir
, dentry
, 1);
2166 if (!dir
->i_op
|| !dir
->i_op
->rmdir
)
2171 mutex_lock(&dentry
->d_inode
->i_mutex
);
2172 dentry_unhash(dentry
);
2173 if (d_mountpoint(dentry
))
2176 error
= security_inode_rmdir(dir
, dentry
);
2178 error
= dir
->i_op
->rmdir(dir
, dentry
);
2180 dentry
->d_inode
->i_flags
|= S_DEAD
;
2183 mutex_unlock(&dentry
->d_inode
->i_mutex
);
2192 static long do_rmdir(int dfd
, const char __user
*pathname
)
2196 struct dentry
*dentry
;
2197 struct nameidata nd
;
2199 name
= getname(pathname
);
2201 return PTR_ERR(name
);
2203 error
= do_path_lookup(dfd
, name
, LOOKUP_PARENT
, &nd
);
2207 switch(nd
.last_type
) {
2218 mutex_lock_nested(&nd
.path
.dentry
->d_inode
->i_mutex
, I_MUTEX_PARENT
);
2219 dentry
= lookup_hash(&nd
);
2220 error
= PTR_ERR(dentry
);
2223 error
= mnt_want_write(nd
.path
.mnt
);
2226 error
= vfs_rmdir(nd
.path
.dentry
->d_inode
, dentry
);
2227 mnt_drop_write(nd
.path
.mnt
);
2231 mutex_unlock(&nd
.path
.dentry
->d_inode
->i_mutex
);
2239 asmlinkage
long sys_rmdir(const char __user
*pathname
)
2241 return do_rmdir(AT_FDCWD
, pathname
);
2244 int vfs_unlink(struct inode
*dir
, struct dentry
*dentry
)
2246 int error
= may_delete(dir
, dentry
, 0);
2251 if (!dir
->i_op
|| !dir
->i_op
->unlink
)
2256 mutex_lock(&dentry
->d_inode
->i_mutex
);
2257 if (d_mountpoint(dentry
))
2260 error
= security_inode_unlink(dir
, dentry
);
2262 error
= dir
->i_op
->unlink(dir
, dentry
);
2264 mutex_unlock(&dentry
->d_inode
->i_mutex
);
2266 /* We don't d_delete() NFS sillyrenamed files--they still exist. */
2267 if (!error
&& !(dentry
->d_flags
& DCACHE_NFSFS_RENAMED
)) {
2268 fsnotify_link_count(dentry
->d_inode
);
2276 * Make sure that the actual truncation of the file will occur outside its
2277 * directory's i_mutex. Truncate can take a long time if there is a lot of
2278 * writeout happening, and we don't want to prevent access to the directory
2279 * while waiting on the I/O.
2281 static long do_unlinkat(int dfd
, const char __user
*pathname
)
2285 struct dentry
*dentry
;
2286 struct nameidata nd
;
2287 struct inode
*inode
= NULL
;
2289 name
= getname(pathname
);
2291 return PTR_ERR(name
);
2293 error
= do_path_lookup(dfd
, name
, LOOKUP_PARENT
, &nd
);
2297 if (nd
.last_type
!= LAST_NORM
)
2299 mutex_lock_nested(&nd
.path
.dentry
->d_inode
->i_mutex
, I_MUTEX_PARENT
);
2300 dentry
= lookup_hash(&nd
);
2301 error
= PTR_ERR(dentry
);
2302 if (!IS_ERR(dentry
)) {
2303 /* Why not before? Because we want correct error value */
2304 if (nd
.last
.name
[nd
.last
.len
])
2306 inode
= dentry
->d_inode
;
2308 atomic_inc(&inode
->i_count
);
2309 error
= mnt_want_write(nd
.path
.mnt
);
2312 error
= vfs_unlink(nd
.path
.dentry
->d_inode
, dentry
);
2313 mnt_drop_write(nd
.path
.mnt
);
2317 mutex_unlock(&nd
.path
.dentry
->d_inode
->i_mutex
);
2319 iput(inode
); /* truncate the inode here */
2327 error
= !dentry
->d_inode
? -ENOENT
:
2328 S_ISDIR(dentry
->d_inode
->i_mode
) ? -EISDIR
: -ENOTDIR
;
2332 asmlinkage
long sys_unlinkat(int dfd
, const char __user
*pathname
, int flag
)
2334 if ((flag
& ~AT_REMOVEDIR
) != 0)
2337 if (flag
& AT_REMOVEDIR
)
2338 return do_rmdir(dfd
, pathname
);
2340 return do_unlinkat(dfd
, pathname
);
2343 asmlinkage
long sys_unlink(const char __user
*pathname
)
2345 return do_unlinkat(AT_FDCWD
, pathname
);
2348 int vfs_symlink(struct inode
*dir
, struct dentry
*dentry
, const char *oldname
)
2350 int error
= may_create(dir
, dentry
, NULL
);
2355 if (!dir
->i_op
|| !dir
->i_op
->symlink
)
2358 error
= security_inode_symlink(dir
, dentry
, oldname
);
2363 error
= dir
->i_op
->symlink(dir
, dentry
, oldname
);
2365 fsnotify_create(dir
, dentry
);
2369 asmlinkage
long sys_symlinkat(const char __user
*oldname
,
2370 int newdfd
, const char __user
*newname
)
2375 struct dentry
*dentry
;
2376 struct nameidata nd
;
2378 from
= getname(oldname
);
2380 return PTR_ERR(from
);
2381 to
= getname(newname
);
2382 error
= PTR_ERR(to
);
2386 error
= do_path_lookup(newdfd
, to
, LOOKUP_PARENT
, &nd
);
2389 dentry
= lookup_create(&nd
, 0);
2390 error
= PTR_ERR(dentry
);
2394 error
= mnt_want_write(nd
.path
.mnt
);
2397 error
= vfs_symlink(nd
.path
.dentry
->d_inode
, dentry
, from
);
2398 mnt_drop_write(nd
.path
.mnt
);
2402 mutex_unlock(&nd
.path
.dentry
->d_inode
->i_mutex
);
2411 asmlinkage
long sys_symlink(const char __user
*oldname
, const char __user
*newname
)
2413 return sys_symlinkat(oldname
, AT_FDCWD
, newname
);
2416 int vfs_link(struct dentry
*old_dentry
, struct inode
*dir
, struct dentry
*new_dentry
)
2418 struct inode
*inode
= old_dentry
->d_inode
;
2424 error
= may_create(dir
, new_dentry
, NULL
);
2428 if (dir
->i_sb
!= inode
->i_sb
)
2432 * A link to an append-only or immutable file cannot be created.
2434 if (IS_APPEND(inode
) || IS_IMMUTABLE(inode
))
2436 if (!dir
->i_op
|| !dir
->i_op
->link
)
2438 if (S_ISDIR(inode
->i_mode
))
2441 error
= security_inode_link(old_dentry
, dir
, new_dentry
);
2445 mutex_lock(&inode
->i_mutex
);
2447 error
= dir
->i_op
->link(old_dentry
, dir
, new_dentry
);
2448 mutex_unlock(&inode
->i_mutex
);
2450 fsnotify_link(dir
, inode
, new_dentry
);
2455 * Hardlinks are often used in delicate situations. We avoid
2456 * security-related surprises by not following symlinks on the
2459 * We don't follow them on the oldname either to be compatible
2460 * with linux 2.0, and to avoid hard-linking to directories
2461 * and other special files. --ADM
2463 asmlinkage
long sys_linkat(int olddfd
, const char __user
*oldname
,
2464 int newdfd
, const char __user
*newname
,
2467 struct dentry
*new_dentry
;
2468 struct nameidata nd
, old_nd
;
2472 if ((flags
& ~AT_SYMLINK_FOLLOW
) != 0)
2475 to
= getname(newname
);
2479 error
= __user_walk_fd(olddfd
, oldname
,
2480 flags
& AT_SYMLINK_FOLLOW
? LOOKUP_FOLLOW
: 0,
2484 error
= do_path_lookup(newdfd
, to
, LOOKUP_PARENT
, &nd
);
2488 if (old_nd
.path
.mnt
!= nd
.path
.mnt
)
2490 new_dentry
= lookup_create(&nd
, 0);
2491 error
= PTR_ERR(new_dentry
);
2492 if (IS_ERR(new_dentry
))
2494 error
= mnt_want_write(nd
.path
.mnt
);
2497 error
= vfs_link(old_nd
.path
.dentry
, nd
.path
.dentry
->d_inode
, new_dentry
);
2498 mnt_drop_write(nd
.path
.mnt
);
2502 mutex_unlock(&nd
.path
.dentry
->d_inode
->i_mutex
);
2506 path_put(&old_nd
.path
);
2513 asmlinkage
long sys_link(const char __user
*oldname
, const char __user
*newname
)
2515 return sys_linkat(AT_FDCWD
, oldname
, AT_FDCWD
, newname
, 0);
2519 * The worst of all namespace operations - renaming directory. "Perverted"
2520 * doesn't even start to describe it. Somebody in UCB had a heck of a trip...
2522 * a) we can get into loop creation. Check is done in is_subdir().
2523 * b) race potential - two innocent renames can create a loop together.
2524 * That's where 4.4 screws up. Current fix: serialization on
2525 * sb->s_vfs_rename_mutex. We might be more accurate, but that's another
2527 * c) we have to lock _three_ objects - parents and victim (if it exists).
2528 * And that - after we got ->i_mutex on parents (until then we don't know
2529 * whether the target exists). Solution: try to be smart with locking
2530 * order for inodes. We rely on the fact that tree topology may change
2531 * only under ->s_vfs_rename_mutex _and_ that parent of the object we
2532 * move will be locked. Thus we can rank directories by the tree
2533 * (ancestors first) and rank all non-directories after them.
2534 * That works since everybody except rename does "lock parent, lookup,
2535 * lock child" and rename is under ->s_vfs_rename_mutex.
2536 * HOWEVER, it relies on the assumption that any object with ->lookup()
2537 * has no more than 1 dentry. If "hybrid" objects will ever appear,
2538 * we'd better make sure that there's no link(2) for them.
2539 * d) some filesystems don't support opened-but-unlinked directories,
2540 * either because of layout or because they are not ready to deal with
2541 * all cases correctly. The latter will be fixed (taking this sort of
2542 * stuff into VFS), but the former is not going away. Solution: the same
2543 * trick as in rmdir().
2544 * e) conversion from fhandle to dentry may come in the wrong moment - when
2545 * we are removing the target. Solution: we will have to grab ->i_mutex
2546 * in the fhandle_to_dentry code. [FIXME - current nfsfh.c relies on
2547 * ->i_mutex on parents, which works but leads to some truely excessive
2550 static int vfs_rename_dir(struct inode
*old_dir
, struct dentry
*old_dentry
,
2551 struct inode
*new_dir
, struct dentry
*new_dentry
)
2554 struct inode
*target
;
2557 * If we are going to change the parent - check write permissions,
2558 * we'll need to flip '..'.
2560 if (new_dir
!= old_dir
) {
2561 error
= permission(old_dentry
->d_inode
, MAY_WRITE
, NULL
);
2566 error
= security_inode_rename(old_dir
, old_dentry
, new_dir
, new_dentry
);
2570 target
= new_dentry
->d_inode
;
2572 mutex_lock(&target
->i_mutex
);
2573 dentry_unhash(new_dentry
);
2575 if (d_mountpoint(old_dentry
)||d_mountpoint(new_dentry
))
2578 error
= old_dir
->i_op
->rename(old_dir
, old_dentry
, new_dir
, new_dentry
);
2581 target
->i_flags
|= S_DEAD
;
2582 mutex_unlock(&target
->i_mutex
);
2583 if (d_unhashed(new_dentry
))
2584 d_rehash(new_dentry
);
2588 if (!(old_dir
->i_sb
->s_type
->fs_flags
& FS_RENAME_DOES_D_MOVE
))
2589 d_move(old_dentry
,new_dentry
);
2593 static int vfs_rename_other(struct inode
*old_dir
, struct dentry
*old_dentry
,
2594 struct inode
*new_dir
, struct dentry
*new_dentry
)
2596 struct inode
*target
;
2599 error
= security_inode_rename(old_dir
, old_dentry
, new_dir
, new_dentry
);
2604 target
= new_dentry
->d_inode
;
2606 mutex_lock(&target
->i_mutex
);
2607 if (d_mountpoint(old_dentry
)||d_mountpoint(new_dentry
))
2610 error
= old_dir
->i_op
->rename(old_dir
, old_dentry
, new_dir
, new_dentry
);
2612 if (!(old_dir
->i_sb
->s_type
->fs_flags
& FS_RENAME_DOES_D_MOVE
))
2613 d_move(old_dentry
, new_dentry
);
2616 mutex_unlock(&target
->i_mutex
);
2621 int vfs_rename(struct inode
*old_dir
, struct dentry
*old_dentry
,
2622 struct inode
*new_dir
, struct dentry
*new_dentry
)
2625 int is_dir
= S_ISDIR(old_dentry
->d_inode
->i_mode
);
2626 const char *old_name
;
2628 if (old_dentry
->d_inode
== new_dentry
->d_inode
)
2631 error
= may_delete(old_dir
, old_dentry
, is_dir
);
2635 if (!new_dentry
->d_inode
)
2636 error
= may_create(new_dir
, new_dentry
, NULL
);
2638 error
= may_delete(new_dir
, new_dentry
, is_dir
);
2642 if (!old_dir
->i_op
|| !old_dir
->i_op
->rename
)
2645 DQUOT_INIT(old_dir
);
2646 DQUOT_INIT(new_dir
);
2648 old_name
= fsnotify_oldname_init(old_dentry
->d_name
.name
);
2651 error
= vfs_rename_dir(old_dir
,old_dentry
,new_dir
,new_dentry
);
2653 error
= vfs_rename_other(old_dir
,old_dentry
,new_dir
,new_dentry
);
2655 const char *new_name
= old_dentry
->d_name
.name
;
2656 fsnotify_move(old_dir
, new_dir
, old_name
, new_name
, is_dir
,
2657 new_dentry
->d_inode
, old_dentry
);
2659 fsnotify_oldname_free(old_name
);
2664 static int do_rename(int olddfd
, const char *oldname
,
2665 int newdfd
, const char *newname
)
2668 struct dentry
* old_dir
, * new_dir
;
2669 struct dentry
* old_dentry
, *new_dentry
;
2670 struct dentry
* trap
;
2671 struct nameidata oldnd
, newnd
;
2673 error
= do_path_lookup(olddfd
, oldname
, LOOKUP_PARENT
, &oldnd
);
2677 error
= do_path_lookup(newdfd
, newname
, LOOKUP_PARENT
, &newnd
);
2682 if (oldnd
.path
.mnt
!= newnd
.path
.mnt
)
2685 old_dir
= oldnd
.path
.dentry
;
2687 if (oldnd
.last_type
!= LAST_NORM
)
2690 new_dir
= newnd
.path
.dentry
;
2691 if (newnd
.last_type
!= LAST_NORM
)
2694 trap
= lock_rename(new_dir
, old_dir
);
2696 old_dentry
= lookup_hash(&oldnd
);
2697 error
= PTR_ERR(old_dentry
);
2698 if (IS_ERR(old_dentry
))
2700 /* source must exist */
2702 if (!old_dentry
->d_inode
)
2704 /* unless the source is a directory trailing slashes give -ENOTDIR */
2705 if (!S_ISDIR(old_dentry
->d_inode
->i_mode
)) {
2707 if (oldnd
.last
.name
[oldnd
.last
.len
])
2709 if (newnd
.last
.name
[newnd
.last
.len
])
2712 /* source should not be ancestor of target */
2714 if (old_dentry
== trap
)
2716 new_dentry
= lookup_hash(&newnd
);
2717 error
= PTR_ERR(new_dentry
);
2718 if (IS_ERR(new_dentry
))
2720 /* target should not be an ancestor of source */
2722 if (new_dentry
== trap
)
2725 error
= mnt_want_write(oldnd
.path
.mnt
);
2728 error
= vfs_rename(old_dir
->d_inode
, old_dentry
,
2729 new_dir
->d_inode
, new_dentry
);
2730 mnt_drop_write(oldnd
.path
.mnt
);
2736 unlock_rename(new_dir
, old_dir
);
2738 path_put(&newnd
.path
);
2740 path_put(&oldnd
.path
);
2745 asmlinkage
long sys_renameat(int olddfd
, const char __user
*oldname
,
2746 int newdfd
, const char __user
*newname
)
2752 from
= getname(oldname
);
2754 return PTR_ERR(from
);
2755 to
= getname(newname
);
2756 error
= PTR_ERR(to
);
2758 error
= do_rename(olddfd
, from
, newdfd
, to
);
2765 asmlinkage
long sys_rename(const char __user
*oldname
, const char __user
*newname
)
2767 return sys_renameat(AT_FDCWD
, oldname
, AT_FDCWD
, newname
);
2770 int vfs_readlink(struct dentry
*dentry
, char __user
*buffer
, int buflen
, const char *link
)
2774 len
= PTR_ERR(link
);
2779 if (len
> (unsigned) buflen
)
2781 if (copy_to_user(buffer
, link
, len
))
2788 * A helper for ->readlink(). This should be used *ONLY* for symlinks that
2789 * have ->follow_link() touching nd only in nd_set_link(). Using (or not
2790 * using) it for any given inode is up to filesystem.
2792 int generic_readlink(struct dentry
*dentry
, char __user
*buffer
, int buflen
)
2794 struct nameidata nd
;
2799 cookie
= dentry
->d_inode
->i_op
->follow_link(dentry
, &nd
);
2801 return PTR_ERR(cookie
);
2803 res
= vfs_readlink(dentry
, buffer
, buflen
, nd_get_link(&nd
));
2804 if (dentry
->d_inode
->i_op
->put_link
)
2805 dentry
->d_inode
->i_op
->put_link(dentry
, &nd
, cookie
);
2809 int vfs_follow_link(struct nameidata
*nd
, const char *link
)
2811 return __vfs_follow_link(nd
, link
);
2814 /* get the link contents into pagecache */
2815 static char *page_getlink(struct dentry
* dentry
, struct page
**ppage
)
2818 struct address_space
*mapping
= dentry
->d_inode
->i_mapping
;
2819 page
= read_mapping_page(mapping
, 0, NULL
);
2826 int page_readlink(struct dentry
*dentry
, char __user
*buffer
, int buflen
)
2828 struct page
*page
= NULL
;
2829 char *s
= page_getlink(dentry
, &page
);
2830 int res
= vfs_readlink(dentry
,buffer
,buflen
,s
);
2833 page_cache_release(page
);
2838 void *page_follow_link_light(struct dentry
*dentry
, struct nameidata
*nd
)
2840 struct page
*page
= NULL
;
2841 nd_set_link(nd
, page_getlink(dentry
, &page
));
2845 void page_put_link(struct dentry
*dentry
, struct nameidata
*nd
, void *cookie
)
2847 struct page
*page
= cookie
;
2851 page_cache_release(page
);
2855 int __page_symlink(struct inode
*inode
, const char *symname
, int len
,
2858 struct address_space
*mapping
= inode
->i_mapping
;
2865 err
= pagecache_write_begin(NULL
, mapping
, 0, len
-1,
2866 AOP_FLAG_UNINTERRUPTIBLE
, &page
, &fsdata
);
2870 kaddr
= kmap_atomic(page
, KM_USER0
);
2871 memcpy(kaddr
, symname
, len
-1);
2872 kunmap_atomic(kaddr
, KM_USER0
);
2874 err
= pagecache_write_end(NULL
, mapping
, 0, len
-1, len
-1,
2881 mark_inode_dirty(inode
);
2887 int page_symlink(struct inode
*inode
, const char *symname
, int len
)
2889 return __page_symlink(inode
, symname
, len
,
2890 mapping_gfp_mask(inode
->i_mapping
));
2893 const struct inode_operations page_symlink_inode_operations
= {
2894 .readlink
= generic_readlink
,
2895 .follow_link
= page_follow_link_light
,
2896 .put_link
= page_put_link
,
2899 EXPORT_SYMBOL(__user_walk
);
2900 EXPORT_SYMBOL(__user_walk_fd
);
2901 EXPORT_SYMBOL(follow_down
);
2902 EXPORT_SYMBOL(follow_up
);
2903 EXPORT_SYMBOL(get_write_access
); /* binfmt_aout */
2904 EXPORT_SYMBOL(getname
);
2905 EXPORT_SYMBOL(lock_rename
);
2906 EXPORT_SYMBOL(lookup_one_len
);
2907 EXPORT_SYMBOL(page_follow_link_light
);
2908 EXPORT_SYMBOL(page_put_link
);
2909 EXPORT_SYMBOL(page_readlink
);
2910 EXPORT_SYMBOL(__page_symlink
);
2911 EXPORT_SYMBOL(page_symlink
);
2912 EXPORT_SYMBOL(page_symlink_inode_operations
);
2913 EXPORT_SYMBOL(path_lookup
);
2914 EXPORT_SYMBOL(vfs_path_lookup
);
2915 EXPORT_SYMBOL(permission
);
2916 EXPORT_SYMBOL(vfs_permission
);
2917 EXPORT_SYMBOL(file_permission
);
2918 EXPORT_SYMBOL(unlock_rename
);
2919 EXPORT_SYMBOL(vfs_create
);
2920 EXPORT_SYMBOL(vfs_follow_link
);
2921 EXPORT_SYMBOL(vfs_link
);
2922 EXPORT_SYMBOL(vfs_mkdir
);
2923 EXPORT_SYMBOL(vfs_mknod
);
2924 EXPORT_SYMBOL(generic_permission
);
2925 EXPORT_SYMBOL(vfs_readlink
);
2926 EXPORT_SYMBOL(vfs_rename
);
2927 EXPORT_SYMBOL(vfs_rmdir
);
2928 EXPORT_SYMBOL(vfs_symlink
);
2929 EXPORT_SYMBOL(vfs_unlink
);
2930 EXPORT_SYMBOL(dentry_unhash
);
2931 EXPORT_SYMBOL(generic_readlink
);